The present invention relates to electrostatographic reproduction machines that produce toner copies of original images, and more particularly to such a machine including a waste toner collecting sump having a verifiably openable shutter assembly for preventing undesirable waste toner spillage within the reproduction machine.
Electrostatographic reproductions such as printers and copiers that use toner for producing copies of original images are well known. For example, such a machine, a copier 10, as disclosed in U.S. Pat. No. 4,849,791, is illustrated as a vertical section in FIG. 1. As is well known, the copier 10 includes a movable image bearing member 12 that is, a photoreceptor having a photoconductive surface, and that is movable about a continuous path. About the path is mounted a series of operational process units. The process units include a charging unit 13 for uniformly charging the photoconductive surface of member 12; an exposure assembly, including a platen 21 for holding an image to be exposed, an exposure lamp 22, and a light transmitting unit 14, for imagewise exposing the charged surface to form a latent image; and a development unit 15 containing toner for developing or making visible the latent image. The process units also include an image transfer unit 16 for transferring a developed image from the surface of member 12 onto a copy sheet fed from a sheet supply 17. The copy sheet is separated from the surface of member 12 with the help of a charging device 18, and is transported through a fusing unit 19 where the toner image is fused, and then into an output tray 20.
After separation of the copy sheet and toner image by the charger unit 18, residual or waste toner remaining on the surface of member 12 is removed by a cleaning unit 27. Cleaning unit 27 includes a conveyor or transport device 28 for moving the waste toner to a collection device or sump, such as to the collection container of the prior art, or to the collecting sump of the present invention (to be described below).
The prior art waste toner collection container and its shutter assembly as disclosed in U.S. Pat. No. 4,849,791, are illustrated in FIGS. 2 and 3. FIG. 2 is a perspective illustration of a cartridge type development unit 15 with a removable conventional waste toner collection sump or container 30 that is attached at one end thereof. As a cartridge, the development unit 15 comes with a cover 32 which when removed upon installation, exposes and positions a toner carrying development roll 34 (FIG. 1) adjacent the photoconductive surface of member 12.
As illustrated, the conventional sump or container 30 includes an opening 36 into a waste toner containing chamber, and a channel-shape sliding shutter 40 that is movable back and forth in the direction of the arrow 42. Edges of flange portions of the channel shutter 40 frictionally ride on the surface of the walls of the sump 30, and the shutter 40 is assembled for such movement by means of an arm 44 connected at one end to a fulcrum pin 46 in a slot 48. At the other end, a two headed pin 50 is provided for movement through a slot 52 in the shutter 40 and a corresponding slot 54 in the body of the sump 30. A fixed path extendable and return linear spring 56 is connected to the shutter 40 and to a fixed location on the sump for allowing the shutter to move in a direction opposite to the spring when the pin 50 is contacted and caused to move through the slots 52 and 54. When properly loaded into a machine such as into the machine 10, the opening 36 will be positioned directly below a discharge end 29 of the waste toner conveyor 28 (FIG. 1).
It has been found that prior art conventional waste toner collection sumps, such as 30, with such a conventional shutter mechanism, suffer from a number of significant disadvantages. In particular, it has been found that the pins 50, which must be brought into contact forcibly with a fixed member within the machine by a cartridge loading force in order to cause them to slide through the slots 52, 54, frequently tend to, and do often break easily. When the pins 50 break as such there is nothing left to cause the shutter 40, (which normally closes the opening 36), to open. The opening 36 therefore remains closed.
More seriously, the shutter 40, even when moved into an open position along the direction of the arrow 42, is hidden from view within the machine and is not visible to an operator looking at the development cartridge 15 and sump 30 from their external end, that is, from a direction as shown by the arrow 58. Therefore, when a pin 50 breaks easily as above and the shutter 40 fails to open, it is not easy or possible, to easily and visually verify such a failure. The undesirable consequences can include the discharge of significant amounts of waste toner into the machine.
There is therefore a need to provide a reproduction machine including a waste toner collection sump assembly having a visually verifiably openable and closable shutter assembly. In addition, there is a need to provide such a reproduction machine wherein the shutter assembly of such a sump is relatively more robust, more easily operated, less costly, and wherein the entire collecting sump is reusable or recyclable, and hence more environmentally friendly.